Met Office: The Unified Model

	The Unified Model

The Unified Model is the name given to the suite of atmospheric and oceanic numerical modelling software developed and used at the Met Office. The formulation of the model supports global and regional domains and is applicable to a wide range of temporal and spatial scales that allow it to be used for both numerical weather prediction and climate modelling as well as a variety of related research activities. The Unified Model was introduced into operational service in 1992. Since then, both its formulation and capabilities have been substantially enhanced. More about the Unified Model system
New Dynamics A major upgrade to the Met Office Global Numerical Weather Prediction model was implemented on 7 August 2002. The package of changes was under trial for over a year and is known as 'New Dynamics'. More about the key changes More about the the development	Submodels The Unified Model is made up of a number of numerical submodels representing different aspects of the earth's environment that influence the weather and climate. Like all coupled models the Unified Model can be split up in a number of different ways, with various submodel components switched on or off for a specific modelling application. More about submodels
Programming the Unified Model The Unified Model was originally written in Fortran 77 but there is provision for machine-specific additions to be made under the configuration management system so that the model runs at near optimal efficiency on the Met Office's supercomputers. Recent work is moving the UM source code towards the Fortran 90 standard with the improved software engineering capabilities it provides. More about Fortran 90 Standards	Unified Model and MPP The trend in architecture of supercomputers in recent years has been towards massively parallel processing (MPP) which means that a program runs on many different processors simultaneously, each processor performing calculations on its own sub-domain independent of those surrounding it. This change necessitated changes in the way that the Unified Model is programmed. More about the Unified Model and MPP
The Ported Unified Model (PUM) Version 6.1 of the Ported Unified Model was released to the user community during March 2006. The code has been tested on several platforms and is made available to university and meteorological institutes for research purposes. More about the Ported Unified Model